Ongoing adjustments due to the tunnel construction. SDOT points out that:

BICYCLE DETOUR UPDATE:

March 30 through April 8 -Bicyclists and pedestrians will be detoured onto East Frontage Road S. between S. Royal Brougham Way and S. Atlantic Street around-the-clock starting at 7 p.m., Wednesday, March 30 until 5 a.m., Friday, April 8. Alaskan Way S. will be closed for construction in this area during this time.

This will affect southbound commuters on this heavily used route; detour should be simple enough.